Thermal analysis of output connector for traveling wave tube

SMA connectors are widely used in mini- traveling wave tube (TWT) as an output power extraction port. The connector is consisted of various materials such as kovar, ceramic, teflon, and monel. In the case of 50 watts output extraction with VSWR 2.5, the generated power in the TWT should be 61 watts. During the passage of this microwave power it is not avoidable to be happened ohmic loss on materials of connector. This ohmic loss is source of heat radiation which should be considered in the TWT design process. This work describes the thermal analysis of output connector as the microwave extraction port of a traveling wave tube amplifier. Considering the tangent loss of various materials consisting connector, we have estimated the ratio of power consumption when microwave passes through the connector by simulation using HFSS (high frequency structure simulator). With the ratio of power consumption on the various materials and assuming of input power, we could designate thermal consumption power which could be used in simulation process with ANSYS code. The result show that the highest temperature appears on the kovar, coaxial centered pin, with 103°C and 180°C in the cases of 50 watts and 100 watts respectively when VSWR is 2.5. Therefore it can be seen that most concerning point is welded part between kovar pin and helix wire, which has reported as most failures has happened with actual devices.